The interbreed data showed that there are 26 informative single nucleotide polymorphisms (SNPs) within the control region that can be useful in determining the haplotype in forensic decisions about whether a particular dog can be included or excluded as a possible source of an evidentiary sample, usually hair. On average, there were 1.9 character changes for each variable position on a phylogenetic tree. The most variable sites (with four or more changes each) were consistent with other reports on variable positions in the dog mtDNA genome. The consistency of the dog dataset with other published sequences supports the utility of this dataset for forensic applications. Tissue samples (blood, heart, liver, testis, and uterus) were collected from dog breeders and veterinary clinics at various locations. The mtDNA analysis is described in detail. Tables show the interbreed analysis for each breed and the intrabreed analysis for Labrador Retrievers and Golden Retrievers. The latter was based on a larger sampling of unrelated dogs from these two select common breeds. Another table shows sequence differences relative to a dog mtDNA reference sequence observed in 45 different canid haplotypes. 5 tables, 1 figure, and 29 references